The invention relates generally to fiberizing spinners and more particularly to a spinner and method of making same, which is assembled from a plurality of peripheral segments and a bottom plate.
The fiberization of glass is typically accomplished by providing a centrifugal spinner and supplying it with a vertically descending stream of molten glass from a forehearth. The spinner is typically supported and rotated on a vertical axis, and the stream of molten glass is fed into the interior and flows to the inner surface of a vertically oriented peripheral wall. The wall defines a large plurality, typically many thousands of, orifices through which the molten glass is centrifugally forced, thereby forming a like plurality of glass streams or fibers external to the spinner. A continuous annular flow of gas, frequently at an elevated temperature, encases the spinner and flows axially downwardly about the periphery of the spinner. The fibers of glass are attenuated by the gas flow. A binder is generally also applied to the glass fibers to improve their adhesion to one another. Finally, the glass fibers are collected upon a foraminous conveyor.
As those familiar with the glass fiberizing process appreciate, the process is, for all intents and purposes, a continuous rather than a batch process. For example, the glass supplied by the forehearth is supplied continuously. Likewise, and desirably, the spinner is constantly rotated, the hot gas for attenuation is provided continuously, and the collection process, typically occurring on a moving conveyor, is also continuous. Often the one feature which interrupts this virtually continuous production process relates to the fiberizing spinner, and more specifically the service life of the fiberizing spinner.
Such spinners operate near the temperature of the molten glass, generally in the range of 1800.degree. to 2000.degree. F. or higher. While these temperatures are substantially below the melting points of the metals and alloys used in such applications, the devices are subject to severe service life constraints.
For example, the elevated operating temperatures and high centrifugal forces to which the periphery of the spinner is subjected create significant difficulties associated with the slow deformation, i.e. creep, of the spinner walls. Eventually this action results in stressrupture failure of the spinner. Furthermore, the molten glass operates to erode the metal and enlarges the orifices of the spinner as it flows therethrough. If this action goes uncompensated, the fiber size increases throughout the life of a given spinner. The fiber size can be adjusted to compensate for orifice diameter change, but eventually sufficient compensation will be unattainable. The elevated operating temperature of the spinner also results in corrosion of the metal by atmospheric agents. The net result of these factors, all operating to deteriorate the spinner, is that the typical service life of a production spinner may be only several hours. When a spinner fails or becomes unserviceable, the production line must be temporarily halted and the spinner replaced. Obviously, a spinner exhibiting improved service life is highly desirable.
Other factors point to the need for improved spinner technology. For example, the vast number of orifices or apertures in a spinner, typically counted in the tens of thousands, are presently most efficiently provided by non-mechanical drilling means such as laser or electron beam drilling. Such drilling processes, while rapid and efficient, are limited by their ability to produce orifices only when properly focused on an object. If the object is nominally circular, such as a fiberizing spinner, but exhibits radial or diametral runout, the drilling beam will lose focus, and thus drilling ability at certain portions of the periphery, and either poorly drill the orifices or completely fail to drill them. Thus, it is essential that the spinner exhibit good circularity in order to ensure the rapid and efficient drilling of the thousands of orifices in the sidewall of the spinner. In the past, this problem has been solved by machining the periphery of the spinner to achieve accurate circularity. This machining step increases the cost of the spinner, and is therefore undesirable. A spinner configuration exhibiting improved circularity, which accordingly eliminates such a machining step, is thus desirable.
Another difficulty of current spinner configurations which results from present production methods is also aggravated by their operating parameters. Because a spinner is rotated at relatively high speeds, typically between 1500 and 2500 rpm., it is essential that the spinner be well balanced. A spinner which is even only slightly out of balance is, ideally, discarded even before it is used, because of its harmful effect on production equipment and its significantly reduced service life. This situation mandates balancing of each individual spinner on equipment which may require significant operator attention, depending on the equipment utilized. A rotor configuration which is the product of improved manufacturing and assembly steps, which eliminate the need for balancing, is thus also highly desirable.